Radio humming

Dr Quick wrote:
I had an older trailer with the same problem when I installed a radio. I changed the radio connection from the converter side of the circuit to the battery side, and hum went away. Figured that any power that the radio used from the battery would be replenished by the converter. Never had any more hum problem.

There are converters, converters and converters.

A 1978 Converter.. I actually had one of these, made by of all folks Progressive Industries had a front panel with a 120 volt outlet, a push to reset breaker and a 3 position toggle labeled Battery/off/And frankly I forget.. This was nothing more than a transformer and a full wave bridge rectifier.. Unflitered DC out, good for lights and not much else.

A very slightly newer one would be the Magnetek 6300 series, this was roughly the same though it had two "Sides" on the 12 volt panel, one was connected to the battery so the battery provided filtering.

What I have today is a Progressive Dynamics 9180 with wizard (Equal to a 9280 with dongle) this is a bit ,,,er,,, much for your trailer but a 9245 or even a 9230 (I think that is the smallest) would be excellent.. This one has very good filtering, IN fact if I accidentally disconnect my batteries when plugged in none of my radios will ever notice except for the ones that are connected DIRECTLY to the battery (They quit when the batteries run down).

Plus the converter babies my batteries which lasted nine years.

Install a battery. Then, install a new converter so it doesn't boil your new battery. Hum problem solved.
Or, buy a small AC powered radio.

I had an older trailer with the same problem when I installed a radio. I changed the radio connection from the converter side of the circuit to the battery side, and hum went away. Figured that any power that the radio used from the battery would be replenished by the converter. Never had any more hum problem.

Golden_HVAC wrote:
Hi,

The 1978 converter is the real problem. However it is somewhat good news, as the converter can be run without a battery in the circuit.

A modern solid state converter/charger will have less hum, but also requires a battery to run the system without power spikes.

You might try a small battery to run the radio. Wire it up so that it can charge from the converter for say 2-4 hours, then wire the 8-track directly to the battery. THen turn on the timer when you want to charge the battery, such as when you are leaving the trailer, and shut it off when you want to use the radio. If you use a switch to charge the battery, and leave it on to long, then the battery can boil out all the water in a short time - the battery might only last about 3-6 months.

If you can buy a cheap 12 volt battery, even a used car battery, or something like that, you can solve your hum problem.

Fred.

You have it backwards.

Older linear converter/power supplies NEED A BATTERY.

They are nothing more than a large transformer and full wave diodes and do not filter or regulate the voltage. They depend on the battery for filtering and regulating the voltage.

Operating a linear converter without a battery presents a very large 60hz or 120hz series of voltage spikes depending on the setup of the diodes.

Yes, you will get some sort of DC voltage but it will have a very large ripple (which is why the OPs stereo is humming). On top of that since the voltage is not regulated it will be somewhere around 16V-18V which can destroy 12V bulbs, pumps, radios and control boards.

Putting in even a used battery is a complete waste of money and time, the converter will turn any battery into a smoldering door stop in short order after it boils all the water out.

Modern converters use a switching power supply and DOES NOT REQUIRE ANY BATTERY TO BE PRESENT in order for it to work.

Modern converters also have multiple stages for battery charging and maintenance. These features drastically reduce the water from boiling out of batteries and will make for a much longer life of the batteries.

OP can get a modern 45A converter from HERE for $160, much better than burning up batteries.

There are many converters.... One end of the spectrum (Thankfully the large end) includes the progressive Dynamics 9180 with wizard I have.. (PDI's wizard controlled units are among the very best,, There is not one model I'd name "THE VERY BEST" but if I had to name just one, this line would be it.)

Back in 1978 the more common was a simply transformer and rectifier thing, no filtering, the output was rectified AC, not really DC and your radio will humm with that kind of power.. Drop in a new battery and it will learn the lyrics for you.

Or better yet, Upgrade to a Progressive dynamics 9235

If converter and power panel are one.. Upgrade only the electroincs and it's a 4600 model more than likely you will need.

Maybe the radio hums 'cuz it doesn't know the words of the new songs it plays... ST

The older converters do not have good filtering; they depend on the battery to filter the DC output.

Like was previously said, even a used battery will cure your problem as long as it doesn't have any shorted cells.

To be clear, you disabled the previous owner speaker wire/power wires? A new ground is more important than positive power. If both power wires are new and home run you may have other ground issues. Using metal staples on speaker/power wire is not ideal. This could create a partial short to ground creating excessive power drain.

Hi,

The 1978 converter is the real problem. However it is somewhat good news, as the converter can be run without a battery in the circuit.

A modern solid state converter/charger will have less hum, but also requires a battery to run the system without power spikes.

You might try a small battery to run the radio. Wire it up so that it can charge from the converter for say 2-4 hours, then wire the 8-track directly to the battery. THen turn on the timer when you want to charge the battery, such as when you are leaving the trailer, and shut it off when you want to use the radio. If you use a switch to charge the battery, and leave it on to long, then the battery can boil out all the water in a short time - the battery might only last about 3-6 months.

If you can buy a cheap 12 volt battery, even a used car battery, or something like that, you can solve your hum problem.

Fred.